Printed circuit boards (PCBs) are present in virtually every electrical device on the market today. PCBs have electrically conductive pathways, or “traces,” running from node to node across the board and, in many cases, through the board to the other side or within layers between board surfaces. PCBs also have plated thru-holes that accept legs of components so as to provide solid electrical connections between the components and the traces.
Previously, all components were attached to PCBs with solder. Removing the components simply required heating the board to the melting point of the solder and pulling the component out of the thru-hole. However, solder is messy, difficult to control and requires multiple processes for application, heating, and cleaning.
To avoid the complications associated with solder, many components became available with press-fit legs. Press-fit legs apply positive pressure to the interior walls of the thru-holes so as to make a solid electrical connection with the plating on the thru-hole walls and to also resist removal from the holes. Each press-fit pin provides about five pounds of resistance to removal.
Virtually all components have multiple pins, which make the needed removal force additive. For instance, some components require as much as 3,000 psi for removal. Therefore, simply pulling a press-fit component to remove it is not a viable removal technique because it results in destruction of the component on the PCB and often times, the PCB itself. The risks associated with this process include damage to the plated thru-hole, uncontrolled debris being lost with the potential of shorting various other components on the board, and scrapping the board entirely due to destruction.
One specific known removal method includes pressing compliant pins from the bottom side of the PCB. However, for several reasons, simply pressing on the compliant pins from the back side is not an efficient removal method. On thicker PCBs, flat rock tooling will not work because the tail does not protrude through the board enough to extract the compliant section of the pin. Great care must be taken to ensure that the removal tool is aligned with all of the thru-holes so that the PTH is not damaged. Given the small physical size of these pins presents a challenge as well. In addition, the compliant tails are not always robust enough to support the extraction force required to press the pin out of the board causing the pin to buckle, scrapping the PCB. Another thing to consider is the pressure on the back side of the PCB, which must be large enough to force all of the pins out, thereby putting great pressure on the board, possibly breaking the board and/or the traces. One additional known method of removing press-fit pins involves pulling of individual pins, often by hand. This method is not a clean process, is not controlled, and is labor intensive.
Therefore a need exists to overcome the problems with the prior art as discussed above.